The present invention relates to an angular indexing device permitting the output shaft to be intermittently rotated with exact index angles and to an angular indexing method utilizing such device.
According to the prior art, as described, for example, in U.S. Pat. No. 3,817,116, an outer peripheral cam including a ridge spirally wound therearound and consisting of a linear portion having a lead angle of 0 and slope portions having relatively large lead angles, respectively, being continuous from said linear portion at opposite ends thereof so that said slope portions at opposite ends are juxtaposed to each other in parallel relationship, is connected to a rotatable shaft of a motor, and each pair of adjacent followers of a rotatable body connected to the output shaft, said rotatable body having a plurality of such followers planted therearound at equal intervals so as to project radially, hold together the ridge of the outer peripheral cam therebetween. The output shaft is maintained stopped together with the rotatable body so long as the followers are in engagement with the ridge of the outer peripheral cam along said linear portion while said outer peripheral cam is rotationally driven at a constant speed by the motor. Upon engagement of the followers with the ridge along its slope portions, the output shaft is rotated together with the rotatable body by a predetermined angle until the next pair of adjacent followers hold the ridge therebetween in engagement with its linear portion, when the output shaft is stopped again. In such angular indexing device for an output shaft of prior art, an accuracy with which the output shaft can be indexed depends upon the precision with which the followers are mounted or planted on the rotatable body. However, working precision of holes formed in the rotatable body into which the respective followers are planted is subject to a certain limitation and it has been impossible, therefore, to improve the output shaft indexing accuracy without improvement of said working precision.